[A writeup by Jaya Prakash Kallikkal on a new concept that can be used by urban planners for building people friendly cities by adoption of technologies aimed at pedestrian traffic, cyclists and alternative mode of passenger and goods movement across cities]
Rapidly shrinking cities owing to rising population and increasing vehicular traffic is a cause of huge concern for individuals and communities in terms of deteriorating health and pollution. We are today witnessing a massive push for construction of roads and metros especially in the cities.
While roads are re-laid over existing tracks, traditional highways are being expanded wider into four and six-lane driveways with varying speed limits. A big causality of urbanization is safe walk ways for pedestrians and cycle tracks for cyclists.
Most cities in India, including Delhi, Chennai, Bengaluru, Hyderabad, Mumbai were proud inheritors of wide green turfs and open lawns. However pressure of urbanization and dwindling land packets due to construction activities and scarcity of spaces has pushed pedestrian traffic out of gear. We are now moving in a direction where less and less space is earmarked for walkers and cyclists, while more and more spaces are being made out for vehicular traffic.
It is a matter of great concern that cities are decaying owing to outright neglect of pedestrians and cyclists who in reality the biggest segment of representing population of a said place. This naturally leads to a question why is this segment being neglected? Is it the phenomenal money power of the automobile industry that is propelling an un-relenting demand for motor vehicles leading to constriction of spaces on roads and cutting into the spaces meant for pedestrians and cyclists?
Though no solution has come to the rescue of this group, it can be noted that the very technology that is pushing growth in terms of adding up of Metro rail in cities can now be used to completely transform the urban landscape.
Current scenario can be radically reformed by design and construction of a network of walkways, subways and inter-segments in the belly of a city that would be revolutionary in not just reducing vehicular clutter in the city but also prove to be the next level of urban landscape. Technology for such activity is already available and can be used for construction of vast passages across the city that could be exclusively used by walkers and cyclists.
Currently multiple types of construction possibilities exist main among them are the Cut-and-cover tunnels which are constructed in a shallow trench and then covered over, another method is Bored tunnels which is constructed on site without removing the ground above. Another method is sinking of pre-fabricated steel or concrete tubes inside trenches where sub soil is immersed in water especially under riverbeds or ocean floors where these tubes are immersed and connected thereby helping in pumping away of water before construction.
Another technology known as Bertha widens the construction options for underground walkways. Bertha is a Japanese technology designed and manufactured by Hitachi Zosen Sakai Works of Osaka is perhaps the world's largest earth pressure balance tunnel boring machine, with a cutter head diameter of 57.5 feet (17.5 m) across. The machine can be as long as 326 feet (99 m) and weighs nearly 6,700 short tons (6,100 t). Another Austrian Technology known as NATM (New Austrian Tunnelling Method) uses conventional tunnel excavation/sequential excavation involves tunnelling through Mechanical excavation and controlled blasting wherein initially the earth is excavated and a primary lining of concrete, steel and lattice girders, wire mesh and rock bolts are applied for stabilizing soil as per geological strata which is reinforced by use of M-25 concrete.
Unless the option of movement and support for environment is not given, cities risk the chances of decay. Underground walkways and cycle tracks are the next generation of planning options that should be part of urban town planners vision. Lack of resources and technology are excuses that administrators and politicians use to divert core issues of development and future vision aimed at benefiting urban masses. It is time Metros and cities in India rise up to the occasion and build up a fascinating underground landscape for movement of people and goods that besides saving fuel and cutting pollution shall go a long way in fostering universal health paving way to a better future for mankind.